The present invention relates to a valve control system for electromagnetically actuating intake and exhaust valves of an internal combustion engine.
While an internal combustion engine is idling, it only requires minimum rotative power enough to keep the engine running, and it is not necessary to burn fuel in all cylinders of the engine. In order to operate the engine with only certain cylinders enabled, the intake and exhaust valves of those cylinders which are disabled should be stopped in operation to eliminate the pumping loss of the disabled cylinders.
Intake and exhaust valves of an internal combustion engine are generally opened and closed by a valve operating mechanism according to a cam profile of a camshaft which rotates in synchronism with the crankshaft of the engine. Various arrangements for stopping the operation of some intake and exhaust valves have been proposed. According to one design, the operation of an intake or exhaust valve is stopped by moving the fulcrum of a rocker arm which transmits the motion of a cam to the valve. According to another scheme, the operation of an intake or exhaust valve is stopped by releasing hydraulic pressure from a hydraulic tappet.
However, the proposed valve disabling devices are structurally complex, and are not satisfactorily reliable when the valve is to be disabled while the engine is in operation.